Hydraulically locked adjustable tail pipe for well tools



Aug. l2, 1969 T. A. RAuGus'r 3,460,619

HYDRAULICALLY LOCKED ADJUSTABLE TAIL PIPE FOR WELL TOOLS Filed Feb. 2v. 1967 2 sheets-sheet 1 /d 5 Afagwaf, ci /Z4/ L ,5 i w, f Z Il: 3. 4 i j? !|u zal Ez@ Z /4 "f5 INVENTOR.

i //aafA Ww/57 Aus- 12, 1969 T. A. RAUGUST 3,460,619

HYDRAULICALLY LOCKED ADJUSTABLE TAIL PIPE FOR WELL TOOLS Filed Feb. 27. 1967 sheets-.sheet a United States Patent O U.S. CL 166--237 6 Claims ABSTRACT OF THE DISCLOSURE The present disclosure relates to an adjustable tail pipe for well tools or packers. The tail pipe is telescopically adjustable from a first position, at which it projects from a packer body to effect setting of the packing means upon engagement of the tail pipe with the bottom of the well and continued downward movement of the packer body relative to the tail pipe, to a second position at which it projects further from the packer body and is hydraulically locked in the second position, thus enabling the packing means to be set at a higher level in the well than when the tail pipe was in the first position. A frangible disc is provided to hold a body of liquid in a piston chamber to hold the telescopic parts against axial movement as the tool is being run into a well and, upon rupture of the frangible disc, an upper tail pipe member is movable upwardly relative to a lower tail pipe member, the piston chamber filling with liquid from the well to prevent return downward movement of the upper tail pipe member, thereby effectively extending the length of the tail pipe and thus the distance above the bottom of the well at which the packer is to be set. The telescopic tail pipe is disclosed in combination with a straddle packer and perforated pipe section of a drill stem tester, wherein the packers are adapted to be set in the open hole.

The present invention relates to a telescopic tail pipe for well tools, and more particularly to a telescopic tail pipe assembly which is adapted to be landed at the bottom of a well such as an oil or gas well, or the like drilled hole, or landed on some other abutment placed in the well, and when landed to cause operation of a well tool thereabove in a running in string of pipe, such as drill pipe or other tubing or well pipe.

In the making of drill stem tests of wells during the drilling operation, a testing apparatus is run into the well on drill pipe, such testing apparatus including means for taking a sample of the fluids in the earth formation about the well bore and between a pair of axially spaced packers which are adapted to be set in the open well bore or open hole so as to straddle the earth formation from which it is desired that the sample be taken, and the packers being separated by a perforated or slotted pipe section into which the formation fluid is to pass. In `some instances the effective bottom of the well is not in a location relative to the zone or formation to be tested as to enable proper setting of the straddle packers by setting a tail pipe down on the bottom of the well. Heretofore, if an improper seal was made by the packers, for example due to the fact that the packers are too low relative to the zone to be straddled, it has been necessary to pull the entire length of drill pipe to change the effective distance between the bottom of tail pipe and the straddle packer. Such an operation is costly and time consuming.

Accordingly, an object of the present invention is to provide a tail pipe construction adapted to operate a well tool, and which is adjustable in Ilength between first and second lengths and having hydraulic locking means for maintaining the tail pipe in an adjusted position.

3,460,619 Patented Aug. 12, 1969 ICC More specifically, an object of the invention is to provide an adjustable tail pipe construction in which an adjustment of the effective length of the tail pipe is made by simple longitudinal manipulation of the pipe string in which the well tool and tail pipe are installed.

Another object is to provide the combination of a well tool adapted to be operated in response to the setting down of the weight of the running in string of pipe, and an adjustable tail pipe and hydraulic lock lalso operated in response to the setting down of the weight of the running in .string of pipe to cause operation of the well tool at an adjusted elevation in the well bore. More specifically, such combination includes a straddle packer of a drill stem tester.

Other objects and advantages of the invention will be hereinafter described or will become apparent to those skilled in the art and the novel features of the invention will be defined in the appended claims.

In brief, the present invention is embodied in an adjustable tail pipe for operating a well tool upon engagement of the tail pipe with the bottom of a well, which includes: an upper body adapted to be connected beneath a well tool, a lower body, one of the bodies having a piston chamber, the other of the bodies having a rod extending into the piston chamber and having piston means at its inner end, check valve means for allowing entry of fluid from the well into the chamber upon telescopic extension of the bodies, and means for preventing the entry of fluid into the chamber through the check valve means, the lastmentioned means being responsive to increased fluid pressure in the chamber caused by telescopic contraction of the bodies upon engagement of the bottom of the well by the lower body to permit entry of fluid through the check valve means. The last-mentioned means may comprise a frangible disc rupturable by fluid pressure in the chamber. Means may also be provided for holding the check valve means open until the frangible disc is ruptured.

In the drawings:

FIG. l is a view generally showing in elevation a drill stem testing tool including a `straddle packer set in a well bore in a first, ineffective position, with the adjustable tail pipe of the invention landed at the bottom of the well;

FIG. 2 is a View generally corresponding to FIG. 1, but showing the tester tool and straddle packer set in a second, effective position in the well bore, with the tail pipe adjusted, hydraulically locked in a position of extended length, Iand landed at the bottom of the well;

FIG. 3 is an enlarged view in vertical section showing the adjustable tail pipe and hydraulic lock in condition as seen in FIG. 1 and just prior to rupture of the frangible member;

FIG. 4 is a view in longitudinal section showing the tail pipe hydraulically locked in its second or extended condition; and

FIG. 5 is a transverse sectional view as taken on the line 5--5 of FIG. 4.

Like reference characters in the `several views of the drawings and in the following description designate corresponding parts.

Referring to FIG. l, there is illustrated a well tool assembly embodying the present invention, such assembly including a hydraulic main valve of conventional construction and forming part of a drill stem tester adapted to be mounted in a running in string of pipe, the tester also including a straddle packer assembly consisting of an upper packer and a lower packer adapted to engage the well bore wall and form spaced seals isolating an intermediate length of perforated pipe into which a sample of for-mation fluid is to be taken. The packers are typically set, or caused to be deformed and moved outwardly into sealing engagement with the well wall in response to the setting down of weight on a tail pipe which depends from the straddle packer assembly, all is as well known in the art.

However, as shown in FIG. 1, the potentially productive earth formation to be tested may consist of narrow sand strata, one of which is designated F. Thus, if the packers do not properly isolate the formation F and one of the packers is disposed in the sandy formation F, an ineffective seal and an ineffective test may result. It is not uncommon in certain oil and gas producing areas that the upper packer may be disposed in an improper location as illustrated in FIG. 1 and the pipe string must be pulled from the well to change the length of the tail pipe so that upon re-running the string of pipe and the new tail pipe, the packers will be properly set as shown in FIG. 2. Such round tripping of the running in string to modify the tool is time consuming and costly. Many such problems may be avoided by adjustment of the effective length of the tail pipe, and in FIG. 2 the vadjustable tail pipe has been extended to raise the location of the packers in the well bore so that they properly isolate the formation F and are engaged with the well wall at locations where better sealing is possible.

The adjustable tail pipe comprises an upper section 1 and a lower tubular section 2 telescopically coengaged and interconnected at 3. Referring to FIG. 3, the structure of the adjustable tail pipe will be described in detail. The body 1 includes a rod 4 which is connected as by a pin and box threaded joint 6 to the lower end of the straddle packer assembly.

The lower body 2 of the tail pipe assembly includes at its upper end a head 7 through which the rod 4 telescopically extends. At its lower end and within the lower body 2 the rod 1 is provided with a piston 8 including an annular seal 9 mounted on a reduced section 10 of the rod and retained thereon by a retaining ring 11 and a nut 12. The seal ring 9 is in the form of a downwardly facing cup of durable material such as Teon so as to sustain substantial pressure without breakage or extrusion into such clearance as exists between the piston 8 and the inner wall of the tubular body 2.

Within the body 2, below piston 8, is a fluid iilled piston chamber 13. At the lower end of the chamber is upwardly opening check valve means including a seat disc 14 mounted in a bore 15 and retained in place by a retainer sleeve 16 which is threaded into the lower end of the body 2. Interposed between the valve seat disc 14 and the retainer 16 is a frangible disc 17 which traps fluid in the piston chamber 13.

A stem 18 extends through the disc 14 and is engaged with frangible disc 17 and with a ball valve 19 so as to normally hold the latter off of the seat against the bias of a spring 20 which is mounted in a bore 21 in the lower end of the body 2. Passages 22 in the lower end of body 2 and passages 23 in the valve seat disc 14 are adapted to establish communication between piston chamber 13 and the well outside the chamber through an open bull nose 24 which is mounted at the lower end of the body 2 and is adapted to land at the bottom of the well. When the tail pipe assembly is in the condition as shown in FIG. 3, however, such communication between the piston chamber 13 and the well is prevented by the disc 17. Under these circumstances the tail pipe may be run into the well and the bull nose 24 landed at the bottom of the well.

Upon the application of the weight of the running in string of pipe to the upper body 1 tending to force rod 4 downwardly with respect to the body 2, fluid pressure applied to the disc 17 will cause the same to be broken out, the pin 18 thus being released from beneath ball valve 19, and the latter then seating on its seat. Thereupon, the trapped fluid in the chamber 13 will hold the piston 8 and rod 4 against further downward movement and the weight of the string of running in pipe will then cause setting of the packers.

If it should appear that the packers, as shown in FIG. 1, are improperly located or otherwise make .an ineicient seal, then, as shown in FIG. 4, the running in string of pipe will be elevated. As the pipe is lifted, moving the packers therewith, the upper body 1 will be moved upwardly relative to the lower 2, and the piston 8 will correspondingly move upwardly. Fluid pressure in the well will unseat ball valve 14, lling the chamber 13. Such relative movement will be limited by abutment of piston 8 with an internal shoulder 8 on the head 7. Just below the shoulder 8 is a passage 2 leading into the body 2 from the well to allow freedom of relative movement of piston 8 in chamber.

Now, when running in string weight is again applied to upper body 1, it will be hydraulically locked against moving downwardly relative to the body 2 by the body of fluid in chamber 13, escape of which is prevented by the seated check valve 19. Thus, the packers may be set in the elevated position shown in FIG. 2.

While the specific details of the invention have been herein shown and described, changes and alterations may be made without departing from the spirit of the invention as defined in the `appended claims.

I claim:

1. In a well tool assembly adapted to be run into a well on a running in string of pipe and including an upper tool and a tail pipe below said tool and engageable with the bottom of the well, said tool having well wall engaging means for engaging the wall of the well responsive to movement of said tool downwardly relative to said tail pipe, the improvement wherein said tail pipe includes a pair of telescopic sections, means for holding said sections against telescopi-c contraction in a rst relative position and in a second relative position wherein said sections are extended, wherein said means for holding includes a piston chamber and a piston slidable therein responsive to relative movement of said sections and a frangible member closing said piston chamber and frangible in response to increased fluid pressure in said piston chamber caused by telescopic contraction of said telescopic sections to permit entry of fluid into said piston chamber upon initial engagement of the bottom of the well by said tail pipe.

2. The well tool of claim 1, wherein said means for holding includes a check valve for allowing said piston chamber to lill with fluid from the well during relative extension of said sections.

3. An adjustable tail pipe for operating a well tool upon engagement of said tail pipe with the bottom of a well, comprising: an upper body adapted to be connected beneath a well tool, a lower body, one of said bodies having a piston chamber, the other of said bodies having a rod extending into said piston chamber and having piston means at its inner end, check valve means for allowing entry of fluid from the well into said chamberupon telescopic extension of said bodies, and means for preventing the entry of fluid into said chamber through said check valve means, said last-mentioned means being responsive to increased Huid pressure in said chamber caused by telescopic contraction of said bodies upon engagement of the bottom of the well by said lower body to permit entry of uid through said check valve means.

4. An adjustable tail pipe as defined in claim 3, wherein said last-mentioned means comprises a frangible disc rupturable by iiuid pressure in said chamber.

5. An adjustable tail pipe as defined in claim 4, wherein means are provided for holding said check valve means open until said frangible disc is ruptured.

6. An adjustable tail pipe as defined in claim 4, wherein said check valve means includes a seat disc, a pin extending through said seat disc and engaged with said frangible disc, a ball valve engaged with said pin and held off of said seat by the latter, and spring means for biasing said ball valve toward said seat disc.

(References on following page) References Cited UNITED STATES PATENTS Taylor 166-186 X Whitaker 166-147 Santiago 166--150 X 5 Chamberlain 166-185 X Hart et al. 166-237 Miller.

6 2,931,438 4/1960 Thompson 166-243 X 3,073,134 1/1963 Mann 166--243 X 3,280,917 10/1966 Ksling 166--152 X CHARLES E. OCONNELL, Primary Examiner IAN A. CALVERT, Assistant Examiner U.S. Cl. X.R. 166-147, 185 

